For example, a multilayer ceramic capacitor is used in a variety of electronic equipment because of high reliability and low cost thereof. Specifically, the multilayer ceramic capacitor is used in information terminals, home electronics, and automobile electronic components. In these use applications, particularly, in a multilayer ceramic capacitor for use application of in-vehicle use or the like, as compared to a typical multilayer ceramic capacitor, securement up to a higher-temperature region is required in some cases and higher reliability is necessary. It is necessary that the multilayer ceramic capacitor is not broken against a voltage to be applied, that is, has high voltage resistance. Further, it is also necessary that insulation resistance is less likely to deteriorate even when a voltage is applied for a long time in a high-temperature region, that is, a high-temperature load life is long.
Patent document 1 discloses a dielectric ceramic composition exhibiting a high specific permittivity at room temperature and having high specific resistance even in a high-temperature range of 180° C. Specifically, disclosed is a technology relating to a multilayer ceramic capacitor using a dielectric ceramic composition containing, as a main component, a tungsten bronze type composite oxide represented by a composition formula (K1−yNay)Sr2Nb5O15 (provided that, 0≤y<0.2) and containing a first sub component and a second sub component in an amount of 0.1 part by mol or more and 40 parts by mol or less with respect to 100 parts by mol of the main component.
However, as understood from the composition formula, in the patent document 1, potassium (K) and sodium (Na) that are alkali metal elements are contained as constituent elements of the main component. Since the alkali metal has high volatility, there is a problem in that handling at the time of manufacturing is prone to be cumbersome, for example, a process of filling an alkali metal element needs to be introduced in processes.
Further, when the alkali metal with high volatility is contained, there are problems in that a lattice defect caused by the alkali metal easily occurs in the dielectric composition by a binder removal process and a firing process that perform a heat treatment at a high temperature, or a reoxidation process, and high voltage resistance is difficult to obtain. Therefore, in the patent document 1, there is no disclosure of a technology relating to a high specific permittivity and high voltage resistance in the high-temperature region.
Further, patent document 2 discloses a technology relating to a ceramic capacitor which includes a dielectric ceramic layer obtained by adding a plurality of additives to a perovskite type oxide formed by a composition formula (Ca1−x(Ba,Sr)x)k(Zr1−yTiy)O3 having a high quality factor Q at 20° C., a favorable temperature coefficient, and high voltage resistance at 150° C.
In the patent document 2, high voltage resistance is exhibited in a high-temperature range of 150° C., but there are problems in that the specific permittivity at 20° C. is only about 125 at a maximum and a desired capacitance is difficult to obtain in a high-temperature region of 175° C. or higher that is expected to be used hereafter.
Further, non-patent document 1 discloses a technology relating to a tungsten bronze type dielectric Ba2MTi2Nb3O15 (M=Bi3+, La3+, Nd3+, Sm3+, Gd3+) with a high specific permittivity and a small dielectric loss. The tungsten bronze type dielectric has a high specific permittivity at room temperature of about 100 to 700 and a favorable value of tan δ at room temperature of 5% or less. In addition, non-patent document 2 discloses a technology relating to a tungsten bronze type dielectric Ba2Sm2Ti4Ta6O30 with a high specific permittivity and a small dielectric loss. The tungsten bronze type dielectric has a high specific permittivity at room temperature of about 120 and a favorable value of tan δ at room temperature of 3% or less. However, the non-patent document 1 does not describe a high-temperature load life.